Like the OP I ended up with this nasty little bugger on my iMac:
Processor 3.4 GHz Intel Core i5
Memory 8GB 1600 MHz DDR3
Software 0s X 10.9.5 (13F1134)
I think I picked up this "bug" last week when I thought I was responding to a prompt to update my adobe flash player. I completed the "update" and safari starting acting strangely. I started getting several pop up screens while trying to complete usual internet activities. For example, if I was on the Amazon site looking for something, I would get pop ups related to whatever I happened to be looking at. I realized I needed to address the issue. The first I did was to download firefox, so as to have a functional browser in case Safari continued to give me issues. Good thing I did, after a few days (keeping mind, I don't spend a whole lot of time on the home computer), Safari would lock up with that darn error message outlined in the OP. It also made it so most of my apps would fail to open, iPhoto, Word, Excel, etc....
Malewarebytes did the trick. I downloaded via firefox, ran it, and a variety of programs were found and deleted. After a system restart, the problem is apparently solved.
I really need to toss those boys (or girls) some cash. I owe 'em!!
For the folks who know a lot more about this stuff then me, and may have an interest, below is the file log of what malwarebytes wiped from my Mac. Perhaps it will be use to someone, I think I would have better luck trying to understand Aramaic
Cheers, Dan
System Log Follows:
2015-11-24 21:10:57 :
2015-11-24 21:10:57 : ----- Scan Started -----
2015-11-24 21:10:57 : Scanning with signatures version 35 (2015-11-24)
2015-11-24 21:10:57 : Adware.InstallCore : /Users/Dad/Library/Application Support/Firefox/Profiles/xynswcp6.default/extensions/{1f7b417d-8a05-471d-abff-b284b629f9d7}
2015-11-24 21:10:57 : Adware.Crossrider : /Users/Dad/Library/LaunchAgents/com.WebShoppers.agent.plist
2015-11-24 21:10:57 : Adware.Crossrider : /Library/LaunchAgents/com.WebShoppers.agent.plist
2015-11-24 21:10:57 : Adware.Crossrider : /Applications/WebShoppers/
2015-11-24 21:10:57 : PUP.Advanced Mac Cleaner : /Library/Application Support/amc/
2015-11-24 21:10:57 : PUP.Advanced Mac Cleaner : /Users/Dad/Library/Advanced Mac Cleaner
2015-11-24 21:10:57 : PUP.Advanced Mac Cleaner : /Users/Dad/Library/hlpramc
2015-11-24 21:10:57 : PUP.Advanced Mac Cleaner : /Users/Dad/Library/Application Support/Advanced Mac Cleaner
2015-11-24 21:10:57 : PUP.Advanced Mac Cleaner : /Users/Dad/Library/LaunchAgents/com.pcv.hlpramc.plist
2015-11-24 21:10:57 : *** scan time: 0d 00:00:00 ***
2015-11-24 21:10:57 : ------ Scan Ended ------
2015-11-24 21:11:38 : ---- File Removal Started ----
2015-11-24 21:11:38 : ===========================================
2015-11-24 21:11:38 : REMOVING ITEM: Adware.InstallCore
2015-11-24 21:11:38 : >> Removing extension item: /Users/Dad/Library/Application Support/Firefox/Profiles/xynswcp6.default/extensions/{1f7b417d-8a05-471d-abff-b284b629f9d7}
2015-11-24 21:11:38 : ===========================================
2015-11-24 21:11:38 : REMOVING ITEM: Adware.Crossrider
2015-11-24 21:11:38 : >> Removing file item: /Users/Dad/Library/LaunchAgents/com.WebShoppers.agent.plist
2015-11-24 21:11:38 : ===========================================
2015-11-24 21:11:38 : REMOVING ITEM: Adware.Crossrider
2015-11-24 21:11:38 : >> Removing file item: /Library/LaunchAgents/com.WebShoppers.agent.plist
2015-11-24 21:11:38 : ===========================================
2015-11-24 21:11:38 : REMOVING ITEM: Adware.Crossrider
2015-11-24 21:11:38 : >> Removing file item: /Applications/WebShoppers/
2015-11-24 21:11:38 : ===========================================
2015-11-24 21:11:38 : REMOVING ITEM: PUP.Advanced Mac Cleaner
2015-11-24 21:11:38 : >> Removing file item: /Library/Application Support/amc/
2015-11-24 21:11:38 : ===========================================
2015-11-24 21:11:38 : REMOVING ITEM: PUP.Advanced Mac Cleaner
2015-11-24 21:11:38 : >> Removing file item: /Users/Dad/Library/Advanced Mac Cleaner
2015-11-24 21:11:38 : ===========================================
2015-11-24 21:11:38 : REMOVING ITEM: PUP.Advanced Mac Cleaner
2015-11-24 21:11:38 : >> Removing file item: /Users/Dad/Library/hlpramc
2015-11-24 21:11:38 : ===========================================
2015-11-24 21:11:38 : REMOVING ITEM: PUP.Advanced Mac Cleaner
2015-11-24 21:11:38 : >> Removing file item: /Users/Dad/Library/Application Support/Advanced Mac Cleaner
2015-11-24 21:11:38 : ===========================================
2015-11-24 21:11:38 : REMOVING ITEM: PUP.Advanced Mac Cleaner
2015-11-24 21:11:38 : >> Removing file item: /Users/Dad/Library/LaunchAgents/com.pcv.hlpramc.plist
2015-11-24 21:11:38 : ---- File Removal Complete ----
2015-11-24 21:11:49 : ===== Attempting restart =====